Fixes 19187 : Specify Length function for PinotDB

[piby180]

Describe your changes:

Fixes #19187

I worked on adding PinotDB to Python Dialect in ORM registry and replacing LEN() with LENGTH() for PinotDB

Type of change:

• Improvement
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• I have read the CONTRIBUTING document.
• My PR title is Fixes <issue-number>: <short explanation>
• I have commented on my code, particularly in hard-to-understand areas.
• For JSON Schema changes: I updated the migration scripts or explained why it is not needed.

[github-actions]

Hi there 👋 Thanks for your contribution!

The OpenMetadata team will review the PR shortly! Once it has been labeled as safe to test, the CI workflows
will start executing and we'll be able to make sure everything is working as expected.

Let us know if you need any help!

[harshach]

Thanks @piby180 for the PR.
@TeddyCr can you review.